The overdrive is 75% complete however I’ve encountered a couple of issues. The first one was the prop shaft bushing that’s mounted in the rear part of the overdrive housing was badly worn and needed replacing. It turns out this part is no longer available but I was able to find a suitable replacement at a local bearing company (only cost a fiver). The only problem with the replacement part is that the external OD of the bush is slightly bigger so I’ve had to take the aluminum housing to the local machine shop to have it bored out. Once this is done I will be able to have the new bush pressed in.
The other issue is that I’m missing a couple of orings that are required for the main operating pistons. It turns out the pistons in the overdrive fitted to the Marcos car is slightly different to the majority of LH type overdrives (eg the ones fitted to MGB’s). The pistons are made from two pieces. This means an extra oring is required and its not supplied in the rebuild kit as standard. When I phone an Overdrive specialist they told me they never normally replaced the orings as it was almost impossible to get the pistons apart. They basically said that if they had a problem with the seals it was cheaper and easier to just replace the whole piston with a solid one, however they didn’t currently have any pistons available for sale.
As the seals in my pistons were not sealing i had no option but to try and dismantle the pistons which i have managed to do so now all I need to do is visit the local bearing company tomorrow and buy a couple of replacement orings